CGAL users discussion list

[Marc Glisse <>]

On Fri, 10 Jul 2015, Marcel wrote:

> i have some trouble with your Straight Skeleton implementation. I call
> several independent instances of the straight skeleton implementation in
> parallel. Unfortunately, with a parallel execution, my program crashes
> with a segmentation fault, double free or corruption or similar errors.
> My code basically looks like the following.
>
> ######
> using CGAL;
> typedef Simple_cartesian<Gmpq> Kernel;

Can you try with mpq_class instead of Gmpq?

> std::vector<Polygon_2<Kernel>> polygons; // non empty set of polygons ;)

Can the different polygons have some point coordinates in common?

> #pragma omp parallel for
> for (size_t i = 0; i < polygons.size(); ++i) {
>          auto skeleton = 
> create_interior_straight_skeleton_2<Polygon_2<Kernel>,
> Kernel>(polygons[i],c);
> }
> ######
>
> A serial execution of my code works flawlessly. Thus, putting the
> straight skeleton computation in a critical section works as well. I've
> tried to define the CGAL_HAS_THREADS macro but as far as I can tell,
> this has no effect. I have incorporated the patch presented in [1] but
> this does not work as well (Note that I am using CGAL 4.6.1).

Hmm, if you tried that patch then it is probably not the issue I was 
thinking about, but it is still useful to check.

> Is this a known issue? Is there a work around?

--
Marc Glisse